Abstract: Casting is one of the oldest and mostly used production processes in industry. The traditional casting has certain disadvantages like poor strength due to hot tears, shrinkage and poor surface finish. The property of casting process mostly depends on the microstructure after solidification. Providing Mould vibration during casting is one of the latest techniques employed in order to get better structure in the solidified casting. Mould vibration during casting gives reduced amount of shrinkage, better morphology, surface finish, and less chances of hot tear. In this research work, the effect of mould vibration during solidification of Aluminum 356alloys for different values of wavelengths at a fixed pouring temperature investigated to understand the modification in microstructure and mechanical properties of casting. The Al356 casting has been prepared in a graphite mould with and without vibrations. The frequencies are varied from 0 Hz to 20 Hz during the casting process. A casting has been made without vibration as well to compare the results of castings with vibration. The experimental results showed significant grain refinement and remarkably improvement in compression strength and hardness of castings with mechanical mould vibration during solidification. Key words: Mould Vibrations, Stir casting, Vibrating table, Ultimate tensile strength, hardness and microstructure.

1. Invention Journal of Research Technology in Engineering & Management (IJRTEM) ISSN: 2455-3689
www.ijrtem.com ǁ Volume 1 ǁ Issue 7 ǁ
| Volume 1 | Issue 7 | www.ijrtem.com | 27 |
An investigation of Effect of Mould Vibrations on Mechanical and
Metallurgical properties of Aluminum 356 Casting
Nagaraju Tenali1
, Dr. B. Karuna Kumar2
, K.Ch. Kishor Kumar3
1
Assistant Professor, Mechanical Engineering Department, Gudlavalleru Engineering College, Sheshadri Rao
Knowledge Village, Gudlavalleru- 521356, Andhra Pradesh, INDIA
2
Professor, Mechanical Engineering Department, Gudlavalleru Engineering College, Sheshadri Rao
Knowledge Village, Gudlavalleru- 521356, Andhra Pradesh, INDIA
3
Associate Professor, Mechanical Engineering Department, Gudlavalleru Engineering College, Sheshadri Rao
Knowledge Village, Gudlavalleru- 521356, Andhra Pradesh, INDIA
Abstract: Casting is one of the oldest and mostly used production processes in industry. The traditional casting has certain
disadvantages like poor strength due to hot tears, shrinkage and poor surface finish. The property of casting process mostly depends on
the microstructure after solidification. Providing Mould vibration during casting is one of the latest techniques employed in order to
get better structure in the solidified casting. Mould vibration during casting gives reduced amount of shrinkage, better morphology,
surface finish, and less chances of hot tear. In this research work, the effect of mould vibration during solidification of Aluminum
356alloys for different values of wavelengths at a fixed pouring temperature investigated to understand the modification in
microstructure and mechanical properties of casting. The Al356 casting has been prepared in a graphite mould with and without
vibrations. The frequencies are varied from 0 Hz to 20 Hz during the casting process. A casting has been made without vibration as
well to compare the results of castings with vibration. The experimental results showed significant grain refinement and remarkably
improvement in compression strength and hardness of castings with mechanical mould vibration during solidification.
Key words: Mould Vibrations, Stir casting, Vibrating table, Ultimate tensile strength, hardness and microstructure.
Introduction
Metal casting is one of the best manufacturing process in which heated liquid metal is poured into the mold cavity and allowed to
solidify in that mould cavity. Out of all the manufacturing process, casting process is cheaper due to its simplified procedure. The
quality of casting depends on the flow behavior of molten metal and other process parameters. In these days more than 85% of
products are produced by casting processes. The totality of metals and alloys begin to work by a very important operation, that of
solidification. Solidification is the operation that gives shape and structure. Currently the solidification technique has experienced a
rapid development. Because of progresses made as yet the castings are used in high security parts in the aero-spatial industry, the
automotive, chemical and metallurgical equipment [1]. Recent techniques suggest that, mold vibration during pouring and till
solidification is one of the important methods to produce casting for better morphology, surface finish and reduced amount of
shrinkage [2]. Mold conditions, pouring temperature, frequency of vibration and other process variables are factors that would have a
definite effect on the microstructure and properties of the cast [3]. It must be noted that above mentioned factors are chosen bearing in
the mind the requirement that the material solidify in a manner that would maximize the properties desired while simultaneously
preventing potential defects such as shrinkage, porosity, voids and trapped inclusions. The most effective method of early fault
detection in a metal cast is high frequency vibration analysis as its parameter changes quickly in the early stages of defect
development. There are mainly three types of vibration such as ultrasonic vibration, electromagnetic vibration and mechanical
vibration [4]. Out of above three methods Mechanical vibration is simple one due to its easier control over its parameters. A number of
researchers have employed ultrasonic and electromagnetic vibration and studied their effect on casting product [5-8].Experimentation
with mold vibration in order to alter the as-cast microstructure of cast components date back to 1868. In one of the earlier
investigations, Chernov [9] found that application of mechanical vibration during solidification of steel caused refinement of austenite.
Sokoloff [10] reported on the use of mechanical vibration for grain refinement. Cambell [11] investigated the mechanical vibration
causes improvement in mechanical and corrosion properties of alloys. Dommaschk [12] studied the effect of vibration on pure
aluminum, Alwt%SiMg alloys along with other non-ferrous alloy. His research focused on the grain refinement and reported that the
dependence of the casting wall thickness on casting characteristics could be minimized with the use of mechanical vibration. S.S.
Mishra [1] the mechanical mold vibration on liquid metallic materials and their crystallization has a significant effect on the grain
structure casting, grain size reduced by vibration and grain became more compact, spheroidal in shape. Pillai [8] used very low
frequency vibration to the study the effect on A356 and Al12Si alloy. He concluded that mechanical vibrations improve the density
and elongation of cast component. Dheir [13] used electromagnetic shaker to induce mechanical vibration in a permanent mold and
concluded that vibration homogenizes the temperature distribution in the mold and promotes more uniform dendrite structure and less
porosity in the castings.

2. An investigation of Effect of Mould Vibrations on Mechanical and Metallurgical properties of Aluminum 356 Casting
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Material selection
Material examined in this project is Aluminium 356. The basic composition and mechanical properties were tabulated in table-1 and
table 2 respectively.
Table 1 Chemical Composition.
Table-2 Mechanical Properties:
Tensile Strength (N/mm2
) Hardness (RBH) Modulus of elasticity (N/mm2
) Elongation(%)
230 75 71 5
Methodology
In this work, methodology consists of two steps. Step one specimen preparation by casting process, Step two testing the specimen as
per standard
A. SPECIMEN PREPARATION
The work was performed in two phases. In first Phase casting the alloys without mould vibration, prepared the baseline for
microstructure and mechanical properties, and. This baseline was used for comparison with corresponding information obtained in
second Phase. In second phase the castings were prepared with mechanical mould vibrations, they were tested as similar of the first
phase. The mechanical mould vibrations were created with pre-determined vibrating table (figure-1).
A set up of vibration mold casting was designed to carry out the casting. The metallic mould (EN8), diameter of the mould was 20mm
and depth of mould cavity was 180mm. The mould was robust to with stand the vibration. The schematic sketch of experimental set
up is shown in the Figure 1. Heating of material (Al-356) carried out in the Muffle Furnace (figure-2) to suitable temperature. The
molten alloy al-356 was cast in a metallic mould coated with zircon paint. From each casting the ingots of Al-356 were cut into
smaller pieces and these pieces were used in the experiments for vibration mould casting. A required amount of Al-356 alloy was
melted in the muffle furnace. The pouring temperature of molten metal kept constant at 720°C. To this molten Al 356 added degassing
agent C2Cl6 then molten metal stirred with a motor operated stirrer. The molten metal was poured into the mould which is on the
vibrating table ready to vibrate. The vibration was applied till the solidification of molten metal. Five numbers of test samples (two for
tensile test, 3 for hardness test and microstructure) were cast for each frequency of vibration. Five numbers of test samples were also
cast without vibration named as casting with 0Hz. Castings were made for different vibration frequencies as from no vibration or 0
Hz, 10Hz, 20 Hz. After casting, all the samples ware processed heat treatment. Some of the (two for each frequency) heat treated
sample were converted into required tensile teat test specimen as per standard. Here used standard is E8. The samples were showed in
figure 3. Reaming heat treated samples were prepared for hardness test and microstructure check up. These hardness and
microstructure samples, each casted one made in to a four equivalent parts along its length. Hardness sample just grinded the surface
by belt grander and followed polishing, the samples are shown in figure 4. The microstructure Samples were prepared by conducting
different metallography steps like polishing on different silicon graded paper, fine polishing on double disc polishing machine and
finally etching. The metallography samples are shown in figure 5.
Figure 1: Vibrating Table Figure 2: Muffle Furnace
Component Si Cu Mg Ti Fe Mn Zn
%Wt 6.5 -7.5 0.2 0.25 -0.45 0.2 0.2 0.2 0.1

3. An investigation of Effect of Mould Vibrations on Mechanical and Metallurgical properties of Aluminum 356 Casting
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Figure- 3(a). Tensile test specimen 0 Hz mould vibrations
Figure- 3(b). Tensile test specimen with 10 Hz mould vibrations
Figure 4: Hardness test specimens
Figure- 3(c). Tensile test specimen with 20 Hz mould vibrations
Figure 5: Microstructure test specimens
Testing
In this work the specimens are examined by conducting tensile test by computerized universal testing machine. The testing conducted
on all frequency (0Hz, 10Hz, and 20Hz) samples the values is tabulated in table 4, 5, 6 and 7. Sample after testing shown in figure 6, 7
and 8. Hardness of the samples examined with rock well harness testing machine. The hardness tested different location of the
samples, the values are tabulated. Metallography examined by Metallurgical microscope with image analysis software the images are
shown in figures 9, 10 and 11.
Results and discussions
A. Tensile test Results
1. Without Mould vibrations 3. With 20Hz Mould vibrations
Table 4: Tensile Test Results without Vibration Table 6: Tensile test results at 20 Hz
2. With 10Hz Mould vibrations
Table 5: Tensile test results at 10 Hz
Table 7: Tensile Test Average Results of Mould Vibration
Graphs are plotted with test results we observed that the tensile strength decreases by increases the mould vibration frequency. As we
know that if tensile strength and compressive strength are reciprocal at tensile strength decreasing the compressive strength increased.
Parameter Range
Temperature range 30 to1000
C
Measuring controlling device 3½ digit led
Chamber size 30 x15 cm
Trail Ultimate Tensile
Strength( N/mm2
)
1 225
2 258
Avg 241
Trail Ultimate tensile
strength (N/mm2
)
1 222
2 202
Avg 212
Trail Ultimate tensile
strength (N/mm2
)
1 221
2 229
Avg 225
FREQUENCY(Hz) ULTIMATE TENSILE
STRENGTH(N/mm2
)
0 241
5 225
10 212

4. An investigation of Effect of Mould Vibrations on Mechanical and Metallurgical properties of Aluminum 356 Casting
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So based on that we can say that if mould vibration increases the compressive strength of the component increases. Tensile results of
vibrated and non-vibrated test samples are shown in table 7 and graph 1.
3. HARDNESS TEST
Hardness results of the cast samples are shown in table 8 & 9. It is clear that hardness of casting increases with the increase in
vibration frequency because vibration causes refinement of grains. The highest hardness is obtained at the bottom of each and every
sample, because highest cooling rate and highest intensity of mould vibration at the bottom of sample, it is evident from the
microstructure. More cooling action promotes creation of fine grain and at the same the vibration procedure fine grains. That means
more grain boundary more hardness. So we may be concluded that due to combined effect of cooling rate and intensity of vibration,
there are remarkable changes of hardness in the cast product. The variation of hardness with mould vibrations are shown in the graph
2 and table 9.
GRAPH 1: Frequency Vs Ultimate Tensile Strength (N/mm2) Graph 2: Frequency (Hz) Vs Hardness (RHB)
A. Microstructure of Different Casted samples
Based on figure 9, it is clearly showing that by increasing the frequency of vibrations the grain refinement increases.
(a): Without vibration (b): With frequency at 5HZ (c): With frequency at 10HZ
Figure 9: Microstructure with and without Vibrations

5. An investigation of Effect of Mould Vibrations on Mechanical and Metallurgical properties of Aluminum 356 Casting
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Hardness Test Results at each vibration and each sample
Table 8: Measurement of Hardness.
TYPE NO OF SPECIMENS HARDNESS(RHB) AVERAGE
(RHB)
NO OF TRALIS
1 2 3
Without vibrations 1 62 60 58 60
2 35 58 74 65
3 62 60 74 65
4 64 67 66 66
With vibrations at 5 HZ 1 84 97 86 89
2 90 87 89 89
3 81 84 83 83
4 90 97 93 93
With vibrations at 10 HZ 1 91 93 93 93
2 86 95 92 91
3 88 92 88 90
4 97 88 91 92
Table 9: Average Hardness Test Results
CONCLUSION
The effect of mechanical mold vibration on mechanical properties casting characteristics of Al-356 alloy was evaluated. Based on the
experimental results there are three main conclusions we can say, one tensile strength by increasing the mould vibration frequency of
the casting the compressive strength increases while tensile strength decreases .The increasing of compressive strength is best sign of
the casted product. Second conclusion by increasing the mould vibration frequency of the casting the hardness values increases. This
is also very good sign. Third and last conclusion that the frequency of mould vibration increasing the grain refinement increases,
which leads to good strength of the casting, Further study can be focused on the effect of poring temperature, effect of frequency more
than 20 Hz. Apart from the above, effect of size variation of the casting and use of different materials can be studied as well.
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